The nature of dark matter (DM) is one of the greatest mysteries of modern physics. It makes
up 25% of the total energy-matter content in the Universe, and is essential for explaining the
large-scale structures we observe in the Universe. Little is known about the nature of dark
matter, and the number of possible theories is vast. However, the most popular dark matter
candidates either solve other, unrelated problems of physics or appear naturally in theories
beyond the Standard Model (BSM). Two such candidates are Weakly Interacting Massive
Particles (WIMPs) and Axion-like Particles (ALPs). This thesis is based on two papers which
study the properties of these two DM candidates and the possible signals they may leave in
detectors at Earth, and in the -ray spectrum of distant astrophysical sources.
Paper I focuses on a class of WIMPs called “inelastic DM” in which the DM particle must
transfer onto a higher-mass state when it interacts with SM particles. In this paper, we have
studied whether such a model can explain the discrepancy between the claimed DM signal in
DAMA and the lack of one in other direct detection experiments.
Paper II focuses on the general class of ALPs, and uses data from the HAWC observatory to
study whether the observed -ray spectra at very high energies from distant blazars are in
conflict with the expected spectra from different ALP models.